Playfully called "Bounce Below," this underground playground is located in the Llechwedd Slate Caverns, a 176-year-old stone quarrying site near Blaenau Ffestiniog, a town in the rain-lashed hills of north Wales.
The caverns are covered in LED lights and nets, with the highest trampoline being suspended 180 feet (55 meters) above the cavern floor.
Back on the surface, there's more fun to be had.
The carved-out slate quarries and mountainsides of Llechwedd are also home to Zip World Titan -- Europe's first multiple zip line, it allows four people to race each other at crazy speeds.
Not the first thing I think of when I think of the Welsh country side but there you have it!
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Bounce Below and Zip World Titan, Llechwedd Slate Caverns, Blaenau Ffestiniog; Bounce Below (£20/$32);
Zip World Titan (£50/$80); +44 1248 601 444

I went cave swimming in Mexico once, and it also involved jumping from high ledges into really, really "deep" places, but there was at least water to for sure slow me down! I'd be worried about those nets though....